1. Field
The present disclosure relates generally to apparatus and methods for updating symbol information in a communication device, and more specifically to using programmable microcode instructions executable by a microcontroller to update symbol information at each symbol including symbol parameters and symbol counts.
2. Background
In recent years, a number of OFDM standards have been proposed for 4G cellular wireless. It is desirable to have a single device act as a common, or “universal”, front-end processor for all such systems. One of the challenges in making such a universal processor is that different wireless standards use different OFDM symbol parameters and different symbol and frame numbering. For example, one OFDM system may employ 8 symbols per frame, while another OFDM system might employ 14 symbols per frame. Also, even systems employing the same standard may be configured in different ways depending on various particular deployment parameters such as bandwidth, cyclic prefix length and Time Division Duplexing (TDD).
The most straightforward method for supporting several standards is to have separate hardware logic for each possible system. However, using dedicated logic for each system configuration leads to unnecessary duplication of hardware, and is not flexible to support new systems and configurations. Another method is to represent the different standards by some set of key OFDM parameters such as FFT length, cyclic prefix length, and framing parameters. The parameters could then be made configurable, generally through registers set by a programmable device such as a DSP.
Unfortunately, symbol and frame numbering across different systems is typically highly irregular and not easily described by a small number of parameters. Also, in some systems like LTE, system parameters such as CP length change on particular symbols, and a number of parameter registers would be needed to describe the timing of those changes. Accordingly, it would be desirable to support several standards in a multimode communication device, such as an OFDM communication device, without the need for separate hardware logic for each standard supported, while also allowing sufficient configurability to support many different systems and a larger number of attendant parameters.